Figure 4. (A) Area of secondary hyperalgesia (means and SD) surrounding the burns and (B) pain responses (means and SD) in the area of secondary hyperalgesia were evaluated using von Frey hair stimuli (462 mN). The legend to Figure 1explains the pain rating. The area of secondary hyperalgesia and the pain response to mechanical stimuli within the zone of secondary hyperalgesia were not inhibited by local or systemic ketamine.